U.S. patent application number 16/627641 was filed with the patent office on 2020-05-21 for radar device.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Shinichi KAMBE, Tatsuya KAMIMURA.
Application Number | 20200158817 16/627641 |
Document ID | / |
Family ID | 65002410 |
Filed Date | 2020-05-21 |
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United States Patent
Application |
20200158817 |
Kind Code |
A1 |
KAMBE; Shinichi ; et
al. |
May 21, 2020 |
RADAR DEVICE
Abstract
A radar device includes a transmission module and a reception
module disposed separately from the transmission module. The
transmission module includes: a transmission circuit unit mounted
on the first surface of a circuit board; an antenna substrate
provided on the second surface side of the circuit board; and a
transmission antenna mounted on the second surface of the antenna
substrate and not provided in a range on the back surface side of
the antenna substrate corresponding to the range in which the
circuit board is disposed. The reception module includes: a
reception circuit unit mounted on the third surface of a circuit
board; an antenna substrate provided on the fourth surface side of
the circuit board; and a reception antenna mounted on the fourth
surface of the antenna substrate and not provided in a range on the
back surface side of the antenna substrate corresponding to the
range in which the circuit board is disposed.
Inventors: |
KAMBE; Shinichi; (Tokyo,
JP) ; KAMIMURA; Tatsuya; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Chiyoda-ku |
|
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Chiyoda-ku
JP
|
Family ID: |
65002410 |
Appl. No.: |
16/627641 |
Filed: |
March 20, 2018 |
PCT Filed: |
March 20, 2018 |
PCT NO: |
PCT/JP2018/011117 |
371 Date: |
December 30, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S 13/003 20130101;
H01Q 1/3233 20130101; H01Q 1/3291 20130101; G01S 13/931 20130101;
H01Q 1/1271 20130101; G01S 2013/93276 20200101; G01S 7/352
20130101; G01S 7/03 20130101 |
International
Class: |
G01S 7/03 20060101
G01S007/03; G01S 7/35 20060101 G01S007/35; H01Q 1/32 20060101
H01Q001/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 11, 2017 |
JP |
2017-135629 |
Claims
1-7. (canceled)
8. A radar device including a transmission module to generate a
radar signal and a reception module to receive a reflected wave of
the radar signal, the transmission module and the reception module
being separately mounted on an automobile, the transmission module
including: a transmission circuit including a first voltage control
oscillator to generate the radar signal on a basis of a reference
signal; and a transmission antenna to emit the radar signal into a
space, the reception module including: a reference oscillator to
generate the reference signal; a reception antenna to receive the
reflected wave of the radar signal from a target object; and a
receiver including: a reception circuit including a second voltage
control oscillator to generate a local signal on the basis of the
reference signal, the reception circuit receiving an output from
the reception antenna on the basis of the local signal; and a
signal processor to calculate target data on the basis of an output
from the reception circuit, wherein the transmission module
includes a first substrate and a first circuit board, the
transmission circuit is mounted on a first surface of the first
circuit board, the first substrate is provided on a second surface
side of the first circuit board, the transmission antenna is
mounted on a second surface of the first substrate, and is not
provided in a corresponding range on a back surface side of the
first substrate, the corresponding range on the back surface side
of the first substrate corresponding to a range in which the first
circuit hoard is disposed on the first substrate, the reception
module includes a second substrate and a second circuit board, the
reception circuit is mounted on a third surface of the second
circuit board, the second substrate is provided on a fourth surface
side of the second circuit board, the reception antenna is mounted
on a fourth surface of the second substrate, and is not provided in
a corresponding range on a back surface side of the second
substrate, the corresponding range on the back surface side of the
second substrate corresponding to a range in which the second
circuit board is disposed on the second substrate, and the second
surface is a surface opposite to the first surface, and the fourth
surface is a surface opposite to the third surface.
9. The radar device according to claim 8, wherein a ground
conductor is provided between the first substrate and the first
circuit board.
10. A radar device including a transmission module to generate a
radar signal and a reception module to receive a reflected wave of
the radar signal, the transmission module and the reception module
being separately mounted on an automobile, the transmission module
including: a transmission circuit to generate the radar signal; and
a transmission antenna to emit the radar signal into a space, the
reception module including: a reception antenna to receive the
reflected wave of the radar signal from a target object; and a
receiver including a reception circuit to receive output from the
reception antenna and a signal processor to calculate target data
on a basis of output from the reception circuit, wherein the
transmission module includes a first substrate and a first circuit
board, the transmission circuit is mounted on a first surface of
the first circuit board, the first substrate is provided on a
second surface side of the first circuit board, the transmission
antenna is mounted on a first surface of the first substrate, the
reception module includes a second substrate and a second circuit
board, the reception circuit is mounted on a third surface of the
second circuit board, the second substrate is provided on a fourth
surface side of the second circuit board, the reception antenna is
mounted on a third surface of the second substrate, the second
surface is a surface opposite to the first surface, and the fourth
surface is a surface opposite to the third surface, and the first
substrate and the second substrate are transparent substrates.
11. The radar device according to claim 8, wherein the transmission
antenna and the transmission circuit are disposed along a first
side of a windshield of the automobile, the reception antenna and
the receiver are disposed along a second side of the windshield of
the automobile, the first side is one of two sides among four sides
of the windshield, the two sides being not parallel to ground, the
four sides of the windshield includes two sides parallel to the
ground, and the second side is an upper one of the two sides
parallel to the ground, the transmission antenna and the reception
antenna are exposed on the windshield, and the transmission circuit
and the reception are accommodated in a structure that supports the
automobile.
12. The radar device according to claim 11, wherein the
transmission circuit is disposed in a front pillar, and the
receiver is disposed in a roof.
13. The radar device according to claim 8, wherein the transmission
circuit includes a plurality of transmission channels, supplies
power to each of the plurality of transmission channels, and
generates the radar signal, the transmission antenna includes a
plurality of transmission antenna element groups defining the
transmission channels, the reception circuit includes a plurality
of reception channels, and receives an output from the reception
antenna at each of the plurality of reception channels, the
reception antenna includes a plurality of reception antenna element
groups defining the reception channels, and the plurality of
transmission antenna element groups and the plurality of reception
antenna element groups form a virtual two-dimensional planar
antenna.
14. The radar device according to claim 13, wherein at least one of
the transmission module and the reception module is plural in
number.
15. A radar device including a transmission module to generate a
radar signal and a reception module to receive a reflected wave of
the radar signal, the transmission module and the reception module
being separately mounted on an automobile, the transmission module
including: a transmission circuit including a first voltage control
oscillator to generate the radar signal on a basis of a reference
signal; and a transmission antenna to emit the radar signal into a
space, the reception module including: a reference oscillator to
generate the reference signal; a reception antenna to receive the
reflected wave of the radar signal from a target object; and a
receiver including: a reception circuit including a second voltage
control oscillator to generate a local signal on the basis of the
reference signal, the reception circuit receiving an output from
the reception antenna on the basis of the local signal; and a
signal processor to calculate target data on the basis of an output
from the reception circuit.
16. The radar device according to claim 15, wherein the
transmission antenna and the transmission circuit are disposed
along a first side of a windshield of the automobile, the reception
antenna and the receiver are disposed along a second side of the
windshield of the automobile, the first side is one of two sides
among four sides of the windshield, the two sides being not
parallel to ground, the four sides of the windshield includes two
sides parallel to the ground, and the second side is an upper one
of the two sides parallel to the ground, the transmission antenna
and the reception antenna are exposed on the windshield, and the
transmission circuit and the receiver are accommodated in a
structure that supports the automobile.
17. The radar device according to claim 15, wherein the
transmission circuit includes a plurality of transmission channels,
supplies power to each of the plurality of transmission channels,
and generates the radar signal, the transmission antenna includes a
plurality of transmission antenna element groups defining the
transmission channels, the reception circuit includes a plurality
of reception channels, and receives an output from the reception
antenna at each of the plurality of reception channels, the
reception antenna includes a plurality of reception antenna element
groups defining the reception channels, and the plurality of
transmission antenna element groups and the plurality of reception
antenna element groups form a virtual two-dimensional planar
antenna.
18. The radar device according to claim 10, wherein the
transmission antenna and the transmission circuit are disposed
along a first side of a windshield of the automobile, the reception
antenna and the receiver are disposed along a second side of the
windshield of the automobile, the first side is one of two sides
among four sides of the windshield, the two sides being not
parallel to ground, the four sides of the windshield includes two
sides parallel to the ground, and the second side is an upper one
of the two sides parallel to the ground, the transmission antenna
and the reception antenna are exposed on the windshield, and the
transmission circuit and the reception are accommodated in a
structure that supports the automobile.
Description
FIELD
[0001] The present invention relates to a radar device for
detecting a target object.
BACKGROUND
[0002] In recent years, the development of radar devices that are
mounted on automobiles to detect target objects has been advanced.
An example of a target object is an automobile that travels in
front of a running automobile equipped with a radar device. Another
example of a target object is an obstacle located in front of a
running automobile equipped with a radar device.
[0003] A radar device includes a transmission antenna and a
reception antenna. The transmission antenna emits radio waves. The
reception antenna receives, from a target object, reflected waves
of the radio waves emitted by the transmission antenna. The radar
device determines the distance from the automobile to the target
object on the basis of the time from the emission of radio waves
from the transmission antenna to the reception of reflected waves
at the reception antenna. Patent Literature 1 below discloses a
high frequency module in which a high frequency package, a
transmission antenna, and a reception antenna are formed as a
single structure.
CITATION LIST
Patent Literature
[0004] Patent Literature 1: Japanese Patent No. 4394147
SUMMARY
Technical Problem
[0005] For the conventional high frequency module, the high
frequency package, the transmission antenna, and the reception
antenna are formed as the single structure, as described above. For
this reason, it is difficult to reduce the size of the high
frequency module. Therefore, the conventional radar device is
problematic because it can be mounted only at a limited place in
the front part of an automobile. An example of the limited place is
a front grille or a bumper.
[0006] The present invention has been made in view of the above,
and an object thereof is to obtain a radar device that can be
mounted at any place on an automobile.
Solution to Problem
[0007] In order to solve the above problem and achieve the object,
a radar device according to the present invention includes a
transmission module to generate a radar signal and a reception
module to receive a reflected wave of the radar signal. The
transmission module and the reception module are separately mounted
on an automobile. The transmission module including: a transmission
circuit unit to generate the radar signal; and a transmission
antenna to emit the radar signal into a space. The reception module
including: a reception antenna to receive the reflected wave of the
radar signal from a target object; and a reception unit including a
reception circuit unit to receive an output from the reception
antenna and a signal processing unit to calculate target data on a
basis of an output from the reception circuit unit. The
transmission module includes a first substrate and a first circuit
board. The transmission circuit unit is mounted on a first surface
of the first circuit board. The first substrate is provided on a
second surface side of the first circuit board. The transmission
antenna is mounted on a second surface of the first substrate, and
is not provided in a corresponding range on a back surface side of
the first substrate, the corresponding range on the back surface
side of the first substrate corresponding to a range in which the
first circuit board is disposed on the first substrate. The
reception module includes a second substrate and a second circuit
board. The reception circuit unit is mounted on a third surface of
the second circuit board. The second substrate is provided on a
fourth surface side of the second circuit board. The reception
antenna is mounted on a fourth surface of the second substrate, and
is not provided in a corresponding range on a back surface side of
the second substrate, the corresponding range on the back surface
side of the second substrate corresponding to a range in which the
second circuit board is disposed on the second substrate. The first
surface and the third surface are front surfaces. The second
surface and the fourth surface are back surfaces.
Advantageous Effects of Invention
[0008] The radar device according to the present invention provides
the effect that the radar device can be mounted at any place on the
automobile.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a diagram illustrating an example of a situation
in which a radar device according to a first embodiment is disposed
in an automobile.
[0010] FIG. 2 is a block diagram illustrating a configuration of
the radar device according to the first embodiment.
[0011] FIG. 3 is a front view and a cross-sectional view
illustrating a transmission module in the first embodiment.
[0012] FIG. 4 is a rear view and a cross-sectional view
illustrating the transmission module in the first embodiment.
[0013] FIG. 5 is a front view and a cross-sectional view
illustrating a reception module in the first embodiment.
[0014] FIG. 6 is a rear view and a cross-sectional view
illustrating the reception module in the first embodiment.
[0015] FIG. 7 is a diagram for explaining the concept of
transmission channels in the first embodiment.
[0016] FIG. 8 is a diagram for explaining the concept of reception
channels in the first embodiment.
[0017] FIG. 9 is a diagram for explaining the concept of a virtual
two-dimensional planar antenna in the first embodiment.
[0018] FIG. 10 is a diagram illustrating an example of a situation
in which a radar device according to a second embodiment is
disposed in an automobile.
[0019] FIG. 11 is a diagram for explaining the concept of a virtual
two-dimensional planar antenna in the second embodiment.
DESCRIPTION OF EMBODIMENTS
[0020] Hereinafter, a radar device according to embodiments of the
present invention will be described with reference to the
accompanying drawings. The present invention is not limited to the
following embodiments. In the following description, physical
connection and electrical connection are not distinguished from
each other and are simply referred to as "connection". In the
accompanying drawings, the scale of each member may be different
from the actual one for easy understanding. Similarly, the scale of
each member in some drawings may be different from that in other
drawings.
First Embodiment
[0021] FIG. 1 is a diagram illustrating an example of a situation
in which a radar device 100 according to the first embodiment is
disposed in an automobile 80. In FIG. 1, the radar device 100
includes a transmission module 40, a reception module 50, and a
connection cable 52. The transmission module 40 generates a high
frequency RAdio Detecting And Ranging (RADAR) signal. The reception
module 50 receives, from a target object, reflected waves of the
radar signal emitted into space.
[0022] The transmission module 40 includes a transmission antenna
15 and a transmission circuit unit 16. The reception module 50
includes a reception antenna 17 and a reception unit 18. As
illustrated in FIG. 1, the transmission module 40 and the reception
module 50, which provide different structures, are separately
mounted on the automobile 80. Since the transmission module 40 and
the reception module 50 are separately provided as the different
structures, both the transmission module 40 and the reception
module 50 can be downsized and thinned.
[0023] The connection cable 52 is a signal connection interface for
transmitting signals between the transmission module 40 and the
reception module 50. An example of the connection cable 52 is an
electrical signal cable including a twisted pair or a coaxial line.
Note that an optical signal cable may be used instead of the
electrical signal cable. Instead of the physical connection cable
52, a technique of transmitting signals using Bluetooth (registered
trademark) or a millimeter wave wireless LAN may be used.
[0024] The automobile 80 includes a windshield 81, a roof 82, and
an A-pillar 83. The roof 82 and the A-pillar 83 are structures that
support the automobile 80.
[0025] A typical car includes a plurality of pillars separated by
windows on its side. The pillars are structures that connect the
body and roof of the car, secure the interior space, and support
the body. Typically, the pillars are designated alphabetically as
the A, B, C, and D-pillars in order from front, but may be called
differently depending on the type of car. Among these pillars, the
illustrated A-pillar 83 is disposed on each side of the windshield
81. In this sense, the A-pillar is also called a "front
pillar".
[0026] The windshield 81 includes four sides. Among the four sides,
two sides not parallel to the ground that is a surface in contact
with the tires (not illustrated) of the automobile 80 are defined
as the first sides. Further, among the four sides, two sides
parallel to the ground are defined as the second sides. The
illustrated second side 81b is the upper one of the two second
sides. The illustrated first side 81a is the right one of the two
first sides, with the automobile 80 viewed from the front of the
automobile 80. The second side 81b intersects the first side 81a.
The term "intersect" means that the second side 81b and the first
side 81a are not parallel.
[0027] On the windshield 81 of the automobile 80, the transmission
antenna 15 is disposed along the first side 81a of the windshield
81 in the upper part of the first side 81a. The reception antenna
17 is disposed along the second side 81b of the windshield 81 in
the middle of the second side 81b.
[0028] The transmission circuit unit 16 is disposed adjacent to the
transmission antenna 15. The transmission antenna 15 is disposed on
the windshield 81, but the transmission circuit unit 16 is
accommodated in the A-pillar 83. Disposing the transmission circuit
unit 16 and the transmission antenna 15 adjacent to each other is
effective in reducing the loss of signal transmission between the
transmission circuit unit 16 and the transmission antenna 15.
[0029] The reception unit 18 is disposed adjacent to the reception
antenna 17. The reception antenna 17 is disposed on the windshield
81, but the reception unit 18 is accommodated in the roof 82.
Disposing the reception unit 18 and the reception antenna 17
adjacent to each other is effective in reducing the loss of signal
transmission between the reception unit 18 and the reception
antenna 17.
[0030] In the exemplary configuration illustrated in FIG. 1, the
transmission antenna 15 is disposed along the right one of the two
first sides 81a of the windshield 81, and the transmission circuit
unit 16 is disposed in the A-pillar 83 located on the right side.
However, the present invention is not limited to this
configuration. The transmission antenna 15 may be disposed along
the left one of the two first sides 81a of the windshield 81, and
the transmission circuit unit 16 may be disposed in the A-pillar 83
located on the left side, with the automobile 80 viewed from the
front of the automobile 80.
[0031] In the example illustrated in FIG. 1, the transmission
antenna 15 and the transmission circuit unit 16 are disposed in the
upper part of the first side 81a. However, the present invention is
not limited to this disposition. The transmission antenna 15 and
the transmission circuit unit 16 may be disposed in the middle of
the first side 81a or in the lower part of the first side 81a.
Where the transmission antenna 15 and the transmission circuit unit
16 are to be disposed in the lower part of the first side 81a, it
should be noted that such disposition ensures that the line of
sight between the transmission antenna 15 and a target object is
not blocked by a structure of the automobile 80.
[0032] In the example illustrated in FIG. 1, the reception antenna
17 and the reception unit 18 are disposed in the middle of the
second side 81b. However, the present invention is not limited to
this disposition. The reception antenna 17 and the reception unit
18 may be disposed in the right or left part of the second side
81b, with the automobile 80 viewed from the front of the automobile
80. In any case, it should be noted that the disposition ensures
that the driver's view is not blocked by the reception antenna 17
exposed on the windshield 81.
[0033] FIG. 2 is a block diagram illustrating a configuration of
the radar device 100 according to the first embodiment. FIG. 2
depicts the configuration of a frequency modulated continuous wave
(hereinafter abbreviated to "FM-CW") radar that uses FM-CW. The
FM-CW radar has features: a simple configuration; and a relatively
low baseband bandwidth, which facilitates signal processes.
[0034] As described above, the radar device 100 according to the
first embodiment includes the transmission module 40 and the
reception module 50. The transmission module 40 includes the
transmission antenna 15 and the transmission circuit unit 16. The
reception module 50 includes the reception antenna 17, a reception
circuit unit 19, and a signal processing unit 20. The reception
unit 18 includes the reception circuit unit 19 and the signal
processing unit 20.
[0035] The transmission circuit unit 16 generates a radar signal.
The transmission antenna 15 emits the radar signal into space as
radio waves. The reception antenna 17 receives, from a target
object, reflected waves of the radar signal emitted into space. The
reception circuit unit 19 receives an output from the reception
antenna 17. More specifically, the reception circuit unit 19
converts a signal in a radio frequency (hereinafter abbreviated to
"RF") band output from the reception antenna 17 to a lower
frequency signal. A signal in the RF band is called an RF signal. A
low frequency signal is called a baseband signal. On the basis of
the baseband signal, the signal processing unit 20 calculates
target data, i.e. data on the target object. The target data
include information on the distance to the target object, the
velocity of the target object, and the orientation of the target
object.
[0036] The transmission antenna 15 includes m transmitting element
antennas 1-1 to 1-m. The transmitting element antennas 1-1 to 1-m
are collectively referred to as the "transmitting element antenna
1". The reference character "m" is the number of channels for a
transmission system. The transmission system is a control system
including the transmission antenna 15 and the transmission circuit
unit 16. It is noted that m is an integer of two or more.
[0037] The reception antenna 17 includes n receiving element
antennas 2-1 to 2-n. The receiving element antennas 2-1 to 2-n are
collectively referred to as the "receiving element antenna 2". The
reference character "n" is the number of channels for a reception
system. The reception system is a control system including the
reception antenna 17 and the reception circuit unit 19. It is noted
that n is an integer of two or more.
[0038] Each of the transmission system and the reception system
performs signal processing on a per channel basis. Channels can be
defined independently for each of the transmission system and the
reception system. Hereinafter, channels for the transmission system
are referred to as "transmission channels", and channels for the
reception system are referred to as "reception channels". The
number of transmission channels m and the number of reception
channels n may be the same or different. The concept of
transmission channels and reception channels will be described
later.
[0039] The transmission circuit unit 16 includes a power
distributor 3, a voltage control oscillator (hereinafter referred
to as "VCO") 4, a modulation circuit 5, and a transmission control
circuit 6. Each element of the transmission circuit unit 16 is made
up of a monolithic microwave integrated circuit (hereinafter
referred to as "MMIC").
[0040] The transmission control circuit 6 applies a control voltage
for operating the power distributor 3, the VCO 4, and the
modulation circuit 5. The transmission control circuit 6 also
receives a command signal from a microcontroller 14 described
later. The transmission control circuit 6 generates a control
signal for controlling the operation of the power distributor 3 and
the VCO 4 in accordance with the command signal.
[0041] The modulation circuit 5 receives, from the microcontroller
14, modulation parameters including the frequency modulation width
and the modulation period. The modulation circuit 5 generates a
modulation signal in accordance with the modulation parameters. The
modulation circuit 5 includes a phase locked loop (hereinafter
abbreviated to "PLL") circuit for stabilizing the modulation signal
through phase synchronization when generating the modulation
signal.
[0042] A reference signal generated by a reference oscillator 13
described later and the modulation signal generated by the
modulation circuit 5 are input to the VCO 4. The VCO 4 generates an
FM-CW signal on the basis of the reference signal and the
modulation signal and outputs the FM-CW signal to the power
distributor 3. The FM-CW signal is a radar signal in the FM-CW
radar.
[0043] The FM-CW signal includes an up-chirp signal in which the
transmission frequency changes from low to high and a down-chirp
signal in which the transmission frequency changes from high to
low. The power distributor 3 distributes power to the transmitting
element antennas 1-1 to 1-m. The distribution of power is performed
by controlling the amplitude and phase for exciting the
transmitting element antennas 1-1 to 1-m.
[0044] The reception unit 18 includes the reception circuit unit 19
and the signal processing unit 20. The reception circuit unit 19
includes mixers 7-1 to 7-n, a VCO 8, a modulation circuit 9,
baseband amplifiers 10-1 to 10-n, analog-to-digital converters
(hereinafter abbreviated to "ADCs") 11-1 to 11-n, and a reception
control circuit 12. Each element of the reception circuit unit 19
is made up of an MMIC. The signal processing unit 20 includes the
reference oscillator 13 and the microcontroller 14 described
above.
[0045] The modulation parameters are transmitted from the
microcontroller 14 are also transmitted to the modulation circuit 9
as well as to the modulation circuit 5 of the transmission circuit
unit 16. The modulation circuit 9 generates a modulation signal in
accordance with the modulation parameters. The modulation circuit 9
includes a PLL circuit for stabilizing the modulation signal
through phase synchronization when generating the modulation
signal.
[0046] The reference signal generated by the reference oscillator
13 and the modulation signal generated by the modulation circuit 9
are input to the VCO 8. On the basis of the reference signal and
the modulation signal, the VCO 8 generates a local signal that is
applied to each of the mixers 7-1 to 7-n.
[0047] Each of reception signals received by the receiving element
antennas 2-1 to 2-n is input to a corresponding one of the mixers
7-1 to 7-n. The mixers 7-1 to 7-n use the local signals generated
by the VCO 8 to down-convert the reception signals to baseband
signals.
[0048] Each of the baseband signals to which the respective mixers
7-1 to 7-n have down-converted the local signals is amplified by a
corresponding one of the baseband amplifiers 10-1 to 10-n. Outputs
from the baseband amplifiers 10-1 to 10-n are analog signals. Each
of the ADCs 11-1 to 11-n converts the output from a corresponding
one of the baseband amplifiers 10-1 to 10-n to a digital
signal.
[0049] The reception control circuit 12 applies a control voltage
for operating the mixers 7-1 to 7-n, the VCO 8, the modulation
circuit 9, the baseband amplifiers 10-1 to 10-n, and the ADCs 11-1
to 11-n.
[0050] The signal processing unit 20 includes the reference
oscillator 13 and the microcontroller 14. The microcontroller 14 is
an example of a computing unit for performing various computations.
Instead of the microcontroller 14, a microprocessor, a
microcomputer, a central processing unit (CPU), or a digital signal
processor (DSP) may be used. Alternatively, instead of the
microcontroller 14, a single circuit, a composite circuit, a
programmed processor, a parallel programmed processor, an
application specific integrated circuit (ASIC), a
field-programmable gate array (FPGA), or a processing circuit
including a combination thereof may be used.
[0051] The microcontroller 14 includes a non-volatile memory 22.
The non-volatile memory 22 stores the modulation parameters
described above. The microcontroller 14 performs computation
processes for calculating target data. The MMICs in the
transmission circuit unit 16 and the MMICs in the reception circuit
unit 19 vary depending on the production lot. For this reason, it
is preferable to store, in the non-volatile memory 22, the
correction amount or correction coefficient individually adjusted
and determined for each product of the transmission module 40 and
the reception module 50. The values of the modulation parameters
described above are corrected by the correction amount or
correction coefficient. The transmission control circuit 6 and the
reception control circuit 12 control the control target components,
using the corrected modulation parameters.
[0052] Next, the configuration of the transmission module 40 in the
first embodiment will be described with reference to FIGS. 3 and 4.
FIG. 3 is a front view and a cross-sectional view illustrating the
transmission module 40 in the first embodiment. In FIG. 3, the
front view of the transmission module 40 is provided on the upper
side, and the cross-sectional view taken along line of the upper
view and seen in the direction of the arrows is provided on the
lower side. FIG. 4 is a rear view and a cross-sectional view
illustrating the transmission module 40 in the first embodiment. In
FIG. 4, the rear view of the transmission module 40 is provided on
the upper side, and the cross-sectional view taken along line IV-IV
of the upper view and seen in the direction of the arrows is
provided on the lower side. In the following description,
right-handed orthogonal coordinate axes are used. That is, the
first direction x1 and the second direction y1 are orthogonal to
each other, and the third direction z1 is orthogonal to both the
first direction x1 and the second direction y1 in a right-handed
system.
[0053] The transmission module 40 includes a circuit board 16c, a
ground conductor 16e, and an antenna substrate 16f in addition to
the transmission antenna 15 and the transmission circuit unit 16
described above. The transmission circuit unit 16 includes
transmission circuit unit integrated circuits (ICs) 16a and
peripheral electronic components 16b.
[0054] The power distributor 3, the VCO 4, the modulation circuit
5, and the transmission control circuit 6 described above are
mounted on the transmission circuit unit ICs 16a. The peripheral
electronic components 16b are electronic components other than the
components mounted on the transmission circuit unit ICs 16a. The
transmission circuit unit ICs 16a are mounted on the circuit board
16c via solder balls 16d. The circuit board 16c is a resin board.
Note that the circuit board 16c may be referred to as the "first
circuit board".
[0055] The circuit board 16c has a planar shape. The planar shape
of the circuit board 16c is a rectangle in which the length Lx1 in
the first direction x1 is larger than the length Ly1 in the second
direction y1. The length Lx1 is in the range of several tens of
millimeters to several hundreds of millimeters. The length Ly1 is
in the range of several millimeters to several tens of
millimeters.
[0056] The transmission circuit unit ICs 16a and the peripheral
electronic components 16b are disposed on one of the two surfaces
of the circuit board 16c. In FIGS. 3 and 4, the one surface is
located on the rear surface side of the transmission module 40. A
normal to the rear surface faces the interior of the automobile 80,
in other words, is directed to the inside of the automobile 80. The
ground conductor 16e is provided on the other of the two surfaces
of the circuit board 16c. In FIGS. 3 and 4, the other surface is
located on the front surface side of the transmission module 40. A
normal to the front surface is directed to the outside of the
automobile 80. Each of the circuit board 16c, the ground conductor
16e, and the antenna substrate 16f has a surface located on the
rear surface side of the transmission module 40 and hereinafter
referred to as the "first surface". Each of the circuit board 16c,
the ground conductor 16e, and the antenna substrate 16f has a
surface located on the front surface side of the transmission
module 40 and hereinafter referred to as the "second surface". A
normal to the first surfaces extends in the negative third
direction z1. A normal to the second surfaces extends in the
positive third direction z1. The first surface is to the second
surface what the "front surface" is to the "back surface".
[0057] The ground conductor 16e has a planar shape. The planar
shape of the ground conductor 16e is a rectangle in which the
length Lx1 in the first direction x1 is larger than the length
Ly1+Ly2 in the second direction y1. The length Ly2 is in the range
of several millimeters to several tens of millimeters.
[0058] The antenna substrate 16f is provided on the second surface
side of the ground conductor 16e. In other words, the ground
conductor 16e is provided on the first surface side of the antenna
substrate 16f. The antenna substrate 16f is a resin substrate. Note
that the antenna substrate 16f may be referred to as the "first
substrate".
[0059] The antenna substrate 16f has a planar shape. The planar
shape of the antenna substrate 16f is a rectangle in which the
length Lx1 in the first direction x1 is larger than the length
Ly1+Ly2 in the second direction y1. In FIGS. 3 and 4, the antenna
substrate 16f has the same shape as the ground conductor 16e, but
may be smaller or larger than the ground conductor 16e.
[0060] The transmission antenna 15 is disposed on the second
surface side of the antenna substrate 16f. The transmission antenna
15 includes sixty four antenna elements 63. An example of each
antenna element 63 is a patch antenna. The sixty four antenna
elements 63 are disposed in sixteen rows along the first direction
x1 and in four rows along the second direction y1 on the second
surface of the antenna substrate 16f. Note that the number of
antenna elements 63 and the number of arrays along the first
direction x1 and the second direction y1 are only examples. The
number of elements and the number of arrays can be determined on
the basis of: the directivity of the transmission antenna 15 in a
plane including the first direction x1 and the third direction z1;
and the directivity of the transmission antenna 15 in a plane
including the second direction y1 and the third direction z1.
[0061] In the configuration of the transmission module 40
illustrated in FIGS. 3 and 4, the portion indicated by the range
"A" is accommodated in the A-pillar 83, and the portion indicated
by the range "B" is exposed to the windshield 81. The range "A" and
the range "B" do not overlap. In other words, the sixty four
antenna elements 63 are not disposed in a corresponding range on
the back surface side of the antenna substrate 16f, which
corresponding range corresponds to the range "A" in which the
circuit board 16c is disposed. This configuration provides the
reduced portion of the transmission module 40 exposed to the
windshield 81, thereby preventing the transmission module 40
mounted on the windshield 81 from obstructing the view from the
driver's seat. In addition, the transmission circuit unit 16
thicker in the third direction z1 than the transmission antenna 15
can be accommodated in the A-pillar 83. This can improve the
mountability of the radar device 100 on the automobile 80. This can
also improve the workability in mounting the radar device 100 on
the automobile 80.
[0062] In the configuration of the transmission module 40
illustrated in FIGS. 3 and 4, the ground conductor 16e is provided.
The presence of the ground conductor 16e facilitates designing the
transmission antenna 15. However, in the configuration of the
transmission module 40 illustrated in FIGS. 3 and 4, the ground
conductor 16e may not be provided. The absence of the ground
conductor 16e simplifies the configuration of the transmission
module 40.
[0063] The antenna substrate 16f may be configured using a
transparent substrate. In a case where the antenna substrate 16f is
a transparent substrate and the ground conductor 16e is not
provided, each of the plurality of antenna elements 63 may be
disposed on the first surface side of the antenna substrate 16f.
Since the transparent substrate has high radio wave permeability,
the antenna elements 63 can be disposed on the first surface side
of the antenna substrate 16f.
[0064] In the case of the configuration in which the antenna
elements 63 are disposed on the first surface side of the antenna
substrate 16f, no protrusion is present on the second surface side
of the antenna substrate 16f. Therefore, the second surface of the
antenna substrate 16f can be formed conforming to the curvature of
the windshield 81. This can improve the workability in mounting the
transmission antenna 15 on the automobile 80.
[0065] Next, the configuration of the reception module 50 in the
first embodiment will be described with reference to FIGS. 5 and 6.
FIG. 5 is a front view and a cross-sectional view illustrating the
reception module 50 in the first embodiment. In FIG. 5, the front
view of the reception module 50 is provided on the left side, and
the cross-sectional view taken along line V-V of the left view and
seen in the direction of the arrows is provided on the right side.
FIG. 6 is a rear view and a cross-sectional view illustrating the
reception module 50 in the first embodiment. In FIG. 6, the rear
view of the reception module 50 is provided on the left side, and
the cross-sectional view taken along line VI-VI of the left view
and seen in the direction of the arrows is provided on the right
side. In the following description, right-handed orthogonal
coordinate axes are used. That is, the fourth direction x2 and the
fifth direction y2 are orthogonal to each other, and the sixth
direction z2 is orthogonal to both the fourth direction x2 and the
fifth direction y2 in a right-handed system.
[0066] The reception module 50 includes a circuit board 19c, a
ground conductor 19e, and an antenna substrate 19f in addition to
the reception antenna 17 and the reception circuit unit 19
described above. The reception circuit unit 19 includes reception
circuit unit ICs 19a and peripheral electronic components 19b.
[0067] The mixers 7-1 to 7-n, the VCO 8, the modulation circuit 9,
the baseband amplifiers 10-1 to 10-n, and the ADCs 11-1 to 11-n
described above are mounted on the reception circuit unit ICs 19a.
The peripheral electronic components 19b are electronic components
other than the components mounted on the reception circuit unit ICs
19a. The reception circuit unit ICs 19a are mounted on the circuit
board 19c via solder balls 19d. The circuit board 19c is a resin
board. Note that the circuit board 19c may be referred to as the
"second circuit board".
[0068] The circuit board 19c has a planar shape. The planar shape
of the circuit board 19c is a rectangle in which the length Lx2 in
the fourth direction x2 is larger than the length Ly3 in the fifth
direction y2. The length Lx2 is in the range of several tens of
millimeters to several hundreds of millimeters. The length Ly3 is
in the range of several millimeters to several tens of
millimeters.
[0069] The reception circuit unit ICs 19a and the peripheral
electronic components 19b are disposed on one of the two surfaces
of the circuit board 19c. In FIGS. 5 and 6, the one surface is
located on the rear surface side of the reception module 50. A
normal to the rear surface faces the interior of the automobile 80,
in other words, is directed to the inside of the automobile 80. The
ground conductor 19e is provided on the other of the two surfaces
of the circuit board 19c. In FIGS. 5 and 6, the other surface is
located on the front surface side of the reception module 50. A
normal to the front surface is directed to the outside of the
automobile 80. Each of the circuit board 19c, the ground conductor
19e, and the antenna substrate 19f has a surface located on the
rear surface side of the reception module 50, and hereinafter
referred to as the "third surface". Each of the circuit board 19c,
the ground conductor 19e, and the antenna substrate 19f has a
surface located on the front surface side of the reception module
50, and hereinafter referred to as the "fourth surface". A normal
to the third surfaces extends in the negative sixth direction z2. A
normal to the fourth surfaces extends in the positive sixth
direction z2. The third surface is to the fourth surface what the
"front surface" is to the "back surface".
[0070] The ground conductor 19e has a planar shape. The planar
shape of the ground conductor 19e is a rectangle in which the
length Lx2 in the fourth direction x2 is larger than the length
Ly3+Ly4 in the fifth direction y2. The length Ly4 is in the range
of several millimeters to several tens of millimeters.
[0071] The antenna substrate 19f is provided on the fourth surface
side of the ground conductor 19e. In other words, the ground
conductor 19e is provided on the third surface side of the antenna
substrate 19f. The antenna substrate 19f is a resin substrate. Note
that the antenna substrate 19f may be referred to as the "second
substrate".
[0072] The antenna substrate 19f has a planar shape. The planar
shape of the antenna substrate 19f is a rectangle in which the
length Lx2 in the fourth direction x2 is larger than the length
Ly3+Ly4 in the fifth direction y2. In FIGS. 5 and 6, the antenna
substrate 19f has the same shape as the ground conductor 19e, but
may be smaller or larger than the ground conductor 19e.
[0073] The reception antenna 17 is disposed on the fourth surface
side of the antenna substrate 19f. The reception antenna 17
includes ninety six antenna elements 73. An example of each antenna
element 73 is a patch antenna. The ninety six antenna elements 73
are disposed in sixteen rows along the fourth direction x2 and in
six rows along the fifth direction y2 on the fourth surface of the
antenna substrate 19f. The number of antenna elements 73 and the
number of arrays along the fourth direction x2 and the fifth
direction y2 are only examples. The number of elements and the
number of arrays can be determined on the basis of: the directivity
of the reception antenna 17 in a plane including the fourth
direction x2 and the sixth direction z2; and the directivity of the
reception antenna 17 in a plane including the fifth direction y2
and the sixth direction z2.
[0074] In the configuration of the reception module illustrated in
FIGS. 5 and 6, the portion indicated by the range "C" is
accommodated in the roof 82, and the portion indicated by the range
"D" is exposed to the windshield 81. The range "C" and the range
"D" do not overlap. In other words, the ninety six antenna elements
73 are not disposed in a corresponding range on the back surface
side of the antenna substrate 19f, which corresponding range
corresponds to the range "C" in which the circuit board 19c is
disposed. This configuration provides the reduced portion of the
reception module 50 exposed to the windshield 81, thereby
preventing the reception module 50 mounted on the windshield 81
from obstructing the view from the driver's seat. In addition, the
reception circuit unit 19 thicker in the sixth direction z2 than
the reception antenna 17 can be accommodated in the roof 82. This
can improve the mountability of the radar device 100 on the
automobile 80. This can also improves the workability in mounting
the radar device 100 on the automobile 80.
[0075] In the configuration of the reception module illustrated in
FIGS. 5 and 6, the ground conductor 19e is provided. The presence
of the ground conductor 19e facilitates designing the reception
antenna 17. However, in the configuration of the reception module
illustrated in FIGS. 5 and 6, the ground conductor 19e may not be
provided. The absence of the ground conductor 19e simplifies the
configuration of the reception module 50.
[0076] The antenna substrate 19f may be configured using a
transparent substrate. In a case where the antenna substrate 19f is
a transparent substrate and the ground conductor 19e is not
provided, each of the plurality of antenna elements 73 may be
disposed on the third surface side of the antenna substrate 19f.
Since the transparent substrate has high radio wave permeability,
the antenna elements 73 can be disposed on the third surface side
of the antenna substrate 19f.
[0077] In the case of the configuration in which the antenna
elements 73 are disposed on the third surface side of the antenna
substrate 19f, no protrusion is present on the fourth surface side
of the antenna substrate 19f. Therefore, the fourth surface of the
antenna substrate 19f can be formed conforming to the curvature of
the windshield 81. This can facilitate improve the workability in
mounting the reception antenna 17 on the automobile 80.
[0078] Next, the concept of transmission channels and reception
channels in the first embodiment will be described with reference
to FIGS. 7 and 8. FIG. 7 is a diagram for explaining the concept of
transmission channels in the first embodiment. FIG. 7 depicts the
transmission antenna 15 extracted from the transmission module 40
illustrated in FIG. 3. FIG. 8 is a diagram for explaining the
concept of reception channels in the first embodiment. FIG. 8
depicts the reception antenna 17 extracted from the reception
module 50 illustrated in FIG. 5.
[0079] In FIG. 7, a first transmission antenna element group 63a
made up of four antenna elements 63 aligned in the second direction
y1 and a second transmission antenna element group 63b made up of
four antenna elements 63 aligned in the second direction y1 are
connected to each other by a line 64. An example of the line 64 is
a microstrip line. The transmission antenna element group including
the eight antenna elements 63 surrounded by a broken line 65 define
one transmission channel. FIG. 7 illustrates a configuration
including eight transmission channels. That is, the number of
transmission channels m is eight in this example.
[0080] In the example of FIG. 7, the first transmission antenna
element group 63a and the second transmission antenna element group
63b are adjacent to each other. However, it is not required that
the first transmission antenna element group 63a and the second
transmission antenna element group 63b be adjacent to each other.
FIG. 7 also illustrates a third transmission antenna element group
63c and a fourth transmission antenna element group 63d. The first
transmission antenna element group 63a and the third transmission
antenna element group 63c may define the first transmission
channel, and the second transmission antenna element group 63b and
the fourth transmission antenna element group 63d may define the
second transmission channel. Alternatively, the first transmission
antenna element group 63a, the second transmission antenna element
group 63b, and the third transmission antenna element group 63c may
define the first transmission channel, and the second transmission
antenna element group 63b, the third transmission antenna element
group 63c, and the fourth transmission antenna element group 63d
may define the second transmission channel.
[0081] In FIG. 8, a first reception antenna element group 73a made
up of six antenna elements 73 aligned in the fifth direction y2 and
a second reception antenna element group 73b made up of six antenna
elements 73 aligned in the fifth direction y2 are connected to each
other by a line 74. An example of the line 74 is a microstrip line.
The reception antenna element group including the 12 antenna
elements 73 surrounded by a broken line 75 defines one reception
channel. FIG. 8 is a configuration including 12 reception channels.
That is, the number of reception channels n is 12 in this
example.
[0082] In the example of FIG. 8, the first reception antenna
element group 73a and the second reception antenna element group
73b are adjacent to each other. However, it is not required that
the first reception antenna element group 73a and the second
reception antenna element group 73b be adjacent to each other. FIG.
8 also illustrates a third reception antenna element group 73c and
a fourth reception antenna element group 73d. The first reception
antenna element group 73a and the third reception antenna element
group 73c may define the first reception channel, and the second
reception antenna element group 73b and the fourth reception
antenna element group 73d may define the second reception channel.
Alternatively, the first reception antenna element group 73a, the
second reception antenna element group 73b, and the third reception
antenna element group 73c may define the first reception channel,
and the second reception antenna element group 73b, the third
reception antenna element group 73c, and the fourth reception
antenna element group 73d may define the second reception
channel.
[0083] FIG. 9 is a diagram for explaining the concept of a virtual
two-dimensional planar antenna 90 in the first embodiment. The
virtual two-dimensional planar antenna can be implemented by
utilizing the concept of transmission channels and reception
channels.
[0084] Assume that a plane parallel to the ground, i.e. a surface
contacting the tires (not illustrated) of the automobile 80 is
referred to as the horizontal plane. Among the planes orthogonal to
the horizontal plane, the plane including the traveling direction
of the automobile 80 that travels in a straight line is referred to
as the vertical plane. As mentioned above, the transmission antenna
15 includes a plurality of transmission channels. In the
transmission antenna 15, power is supplied to each of the plurality
of transmission channels. If power is supplied using different
excitation phases for the plurality of transmission channels, beam
scanning in the vertical plane can be performed at the transmission
antenna 15.
[0085] As mentioned above, the reception antenna 17 includes a
plurality of reception channels. If reception is performed at each
of the plurality of reception channels, beam scanning in the
horizontal plane can be performed at the reception antenna 17.
[0086] Therefore, the radar device 100 according to the first
embodiment can control directivity in both the vertical plane and
the horizontal plane by performing beam scanning in the vertical
plane using the transmission antenna 15 and by performing beam
scanning in the horizontal plane using the reception antenna
17.
[0087] The directivity of the transmission antenna 15 may be
controlled by causing the plurality of transmission channels of the
transmission antenna 15 to emit radio waves with different phases.
The emission of radio waves from the plurality of transmission
channels of the transmission antenna 15 may be performed using time
division, in which case, after radio waves are received by the
reception antenna 17, a plurality of digital signals corresponding
to the received radio waves can be reconstructed. Each of the
plurality of transmission channels of the transmission antenna 15
may emit radio waves having different codes, in which case, after
radio waves are received by the reception antenna 17, signals
corresponding to the respective channels can be separated on the
basis of the codes.
[0088] Since the positions of the plurality of transmission
channels of the transmission antenna 15 are different from one
another, the transmission antenna 15 emits radio waves with
different phases in different directions. Therefore, the phase of
the signal corresponding to each of the radio waves received by the
reception antenna 17 varies depending on the transmission channel
of the transmission antenna 15. That is, from the radio waves
received by the reception antenna 17, signals equivalent to signals
that are received by the virtual two-dimensional planar antenna 90
illustrated in FIG. 9 are obtained.
[0089] In FIG. 9, each part surrounded by a broken line represents
a virtual transmission/reception channel. Each
transmission/reception channel is assigned a label "Rp, q" using a
natural number p and a natural number q. The natural number p of
the label "Rp, q" indicates the identification number of the
transmission channel, and the natural number q of the label "Rp, q"
indicates the identification number of the reception channel.
[0090] In FIG. 9, the virtual reception antenna in the first row
and the first column represents the antenna in a case where a
signal from the first transmission channel of the transmission
antenna 15 is received at the first reception channel of the
reception antenna 17. The virtual reception antenna in the second
row and the second column represents the antenna in a case where a
signal from the second transmission channel of the transmission
antenna 15 is received at the second reception channel of the
reception antenna 17. The same applies to the others. The angle of
a reflected wave is estimated by multiplying the signal
corresponding to the virtual two-dimensional planar antenna of FIG.
9 by the phase for forming a beam in an arbitrary direction. Since
the transmission antenna element groups defining the transmission
channels and the reception antenna element groups defining the
reception channels are disposed virtually and two-dimensionally,
beams can be formed not only in the horizontal and vertical planes
but also in oblique directions.
[0091] As described above, the radar device 100 according to the
first embodiment includes the transmission antenna and the
transmission circuit unit disposed along the first side of the
windshield of the automobile and the reception antenna and the
reception unit disposed along the second side of the windshield of
the automobile. The first side is one of the two sides among the
four sides of the windshield, which two sides are not parallel to
the ground. The second side is the upper one of the two sides among
the four sides of the windshield, which two sides are parallel to
the ground. The transmission antenna and the reception antenna are
exposed on the windshield. The transmission circuit unit and the
reception unit are accommodated in the structures that support the
automobile. The windshield has a larger area than the front grille
and the bumper, thus enabling flexible dispositions. Therefore, the
radar device 100 according to the first embodiment can be mounted
at any place on the automobile, which is effective.
Second Embodiment
[0092] FIG. 10 is a diagram illustrating an example of a situation
in which a radar device 100A according to the second embodiment is
disposed in the automobile 80. As illustrated in FIG. 10, the radar
device 100A includes transmission modules 40a, 40b, and 40c, the
reception module 50, and the connection cable 52. Each of the
transmission modules 40a, 40b, and 40c is the same component as the
transmission module 40 described in the first embodiment. That is,
the radar device 100A according to the second embodiment uses three
separate transmission modules each of which is the transmission
module 40 described in the first embodiment. As in the first
embodiment, each of the transmission modules 40a, 40b, and 40c
includes the transmission circuit unit 16 accommodated in the
A-pillar 83 and the transmission antenna 15 exposed on the
windshield 81. Thus, the radar device 100A according to the second
embodiment forms a virtual two-dimensional planar antenna using the
three transmission modules 40 and the one reception module 50.
[0093] FIG. 11 is a diagram for explaining the concept of a virtual
two-dimensional planar antenna 90A in the second embodiment.
[0094] In FIG. 11, the virtual transmission/reception channel in
the first row and the first column represents the
transmission/reception channel in a case where a signal from the
first transmission channel of the transmission antenna 15 of the
transmission module 40a is received at the first reception channel
of the reception antenna 17. The virtual transmission/reception
channel in the eighth row and the eighth column represents the
transmission/reception channel in a case where a signal from the
eighth transmission channel of the transmission antenna 15 of the
transmission module 40a is received at the eighth reception channel
of the reception antenna 17.
[0095] Further, in FIG. 11, the virtual transmission/reception
channel in the ninth row and the first column represents the
transmission/reception channel in a case where a signal from the
first transmission channel of the transmission antenna 15 of the
transmission module 40b is received at the first reception channel
of the reception antenna 17. Considering the transmission antenna
15 of the transmission module 40a and the transmission antenna 15
of the transmission module 40b to be one virtual transmission
antenna 15 enables the first transmission channel of the
transmission antenna 15 of the transmission module 40b to be
virtually handled as the ninth transmission channel. Therefore,
this virtual transmission/reception channel can be handled with the
label "R9, 1" assigned. The same applies to the others.
[0096] Further, in FIG. 11, the virtual transmission/reception
channel in the seventeenth row and the first column represents the
transmission/reception channel in a case where a signal from the
first transmission channel of the transmission antenna 15 of the
transmission module 40c is received at the first reception channel
of the reception antenna 17. Considering the transmission antenna
15 of the transmission module 40a, the transmission antenna 15 of
the transmission module 40b, and the transmission antenna 15 of the
transmission module 40c to be one virtual transmission antenna 15
enables the first transmission channel of the transmission antenna
15 of the transmission module 40c to be virtually handled as the
seventeenth transmission channel. Therefore, this virtual
transmission/reception channel can be handled with the label "R17,
1" assigned. The same applies to the others.
[0097] Referring to FIG. 10, the transmission modules 40a, 40b, and
40c are disposed along the A-pillar 83, which extends the length of
the transmission antenna 15 in the first direction x1, namely the
longitudinal length of the transmission antenna 15. Generally, the
area of an antenna is substantially proportional to its gain, and
the observable distance increases as the area becomes larger.
Therefore, the extension of the longitudinal length of the
transmission antenna 15 can improve the detection performance.
[0098] In addition, the extension of the longitudinal length of the
transmission antenna 15 can reduce the beam width in the vertical
plane, so that the resolution in the vertical plane can be
improved.
[0099] Although FIG. 10 illustrates an example in which the three
transmission modules 40 and the one reception module 50 define the
virtual two-dimensional planar antenna 90A, the present invention
is not limited to this configuration. The number of transmission
modules 40 may be other than three, and the number of reception
modules 50 may be plural. The plural reception modules 50 can
improve the detection performance and the resolution in the
horizontal plane more than the one reception module 50.
[0100] As described above, the radar device 100A according to the
second embodiment can form the virtual two-dimensional planar
antenna 90A using the plurality of transmission antenna element
groups defining the transmission channels and the plurality of
reception antenna element groups defining the reception channels.
Consequently, the effect of improving the detection performance,
the resolution in the vertical plane, and the resolution in the
plane can be achieved.
[0101] Note that the configurations described in the
above-mentioned embodiments indicate examples of the contents of
the present invention. The configurations can be combined with
another well-known technique, and some of the configurations can be
omitted or changed in a range not departing from the gist of the
present invention.
REFERENCE SIGNS LIST
[0102] 1, 1-1 to 1-m transmitting element antenna; 2, 2-1 to 2-n
receiving element antenna; 3 power distributor; 4, 8 VCO; 5, 9
modulation circuit; 6 transmission control circuit; 7-1 to 7-n
mixer; 10-1 to 10-n baseband amplifier; 11-1 to 11-n ADC; 12
reception control circuit; 13 reference oscillator; 14
microcontroller; 15 transmission antenna; 16 transmission circuit
unit; 16a transmission circuit unit IC; 16b, 19b peripheral
electronic component; 16c, 19c circuit board; 16d, 19d solder ball;
16e, 19e ground conductor; 16f, 19f antenna substrate; 17 reception
antenna; 18 reception unit; 19 reception circuit unit; 19a
reception circuit unit IC; 20 signal processing unit; 22
non-volatile memory; 40, 40a, 40b, 40c transmission module; 50
reception module; 52 connection cable; 63, 73 antenna element; 63a
first transmission antenna element group; 63b second transmission
antenna element group; 63c third transmission antenna element
group; 63d fourth transmission antenna element group; 64, 74 line;
73a first reception antenna element group; 73b second reception
antenna element group; 73c third reception antenna element group;
73d fourth reception antenna element group; 80 automobile; 81
windshield; 81a first side; 81b second side; 82 roof; 83 A-pillar;
90, 90A two-dimensional planar antenna; 100, 100A radar device.
* * * * *